Nozzle and control apparatus

ABSTRACT

An improved fluidic nozzle and fluid-flow control apparatus is described. Control apparatus for altering the path of fluid flow in the nozzle, including chambers capable of being selectively opened and closed for creating pressure imbalances are shown.

United States Patent Inventors Gordon P Johnson St. Paul; Le Roy E.Ger-loch, Minneapolis, both of Minn. App]. No. 791,239 Filed Jan. 15,I969 Patented Dec. 21, 1971 Assignee Sperry Rand Corporation New York,N.Y.

NOZZLE AND CONTROL APPARATUS 6 Chill, 5 Drawing Figs.

Us. Cl 239/10], 239/l 02, 239/265.l7, 23914255 Int. Cl B05b 1/08I'ieldolSearch 239/l0l,

smcnnomzme CONTROL FLUID SOURCE PRESSURE [56] References Cited UNITEDSTATES PATENTS 3,0l6,699 l/l962 Bertin et al. 239/l65.l7 3,l 32,476 5/ l964 Conrad;- 239/265. 1 7 3,144,752 8/ I964 Kepler'..' 239/26S.l73,l66,897 III 965 Lawrence et al. 239/265. l 7 3,302,884 2/ l 967Robinson 239/265. l 7 3,370,794 211968 Drewry et al. 239/265. l 73,426,972 2/1969 Osburn 238/265. l 7

Primary Examiner-Lloyd L. King Attorneys-Thomas .I. Nikolai, Kenneth T.Grace and John P.

Dority ABSTRACT: An improved fluidic nozzle and fluid-flow controlapparatus is described. Control apparatus for altering the path of fluidflow in the nozzle, including chambers capable of being selectivelyopened and closed for creating pressure ifiibalances are shown. 1

CONTROL CONTmL 2O l FLUID FLOW \4 PORT B CONTROL PATENTEDBECZY ml PORT ACONTROL SYNCHRONIZING CONTROL PORT B CONTROL FLUID SOURCE PRESSURECONTROL INVENTORS GORDON I? JOHNSON LEROY E. GERLACH BY 5440f NOZZLE ANDCONTROL APPARATUS BACKGROUND OF THE INVENTION l. Field of the InventionThis invention relates to fluid nozzles; and, more specifically, relatesto improved control apparatus for use with the so-called Prandtl nozzle.

2. Description of the Prior Art The so-called Prandtl nozzle is known tothe prior art. This nozzle generally has a neck portion for receiving afluid flow, and expands in a bell-like fashion at the exhaust end. Inthe absence of applied control, the fluid will normally flow directlythrough the Prandtl nozzle from the neck portion straight or through thebell-like exhaust end. It is known, that by the injection of a fluidpressure along the neck portion approximately in the vicinity of theexpanding bell-like exhaust portion, that the fluid will be forced awayfrom the injected fluid pressure and will tend to adhere to the oppositeportion of the nozzle. This adherence of the fluid to the wall of thenozzle, is referred to as the Coanda effect, or alternatively aswall-attachment effect. The fluid flow will therefore be deflected atthe exhaust end away from the straight line flow, and will continue inthis deflected manner even in the absence of the continued injection ofthe directing fluid impulses. In order to cause the flow to deflect inthe opposite direction, a fluid impulse must be injected at the oppositeside of the nozzle, thereby causing the fluid to be deflected toward andadhereto the opposite wall of the nozzle. In order to get the fluid flowdirectly through the nozzle, it was necessary to inject fluid signals toboth sides of the Prandtl nozzle, thereby causing the flow of fluid tobe detached from each of the walls. Alternatively, a fluid impulse couldbe injected along the wall to which the fluid flow was attached, but ofan impulse level insufficient to force the fluid flow to the oppositewall. This prior art arrangement for switching the direction of fluidflow at the output of the Prandtl nozzle had the drawback of requiringseparate sources of fluid pressure and control for causing the switchingof the direction of fluid flow, and required the additional controlelements for the switching and gating of the controlling fluid impulses.Further, it was necessary to provide controls for establishing thelevel, or force, and the duration of such controlling fluid impulses.

SUMMARY In summary, then, this invention comprises an improved Prandtlnozzle that does not require the application of fluidic impulses forcontrolling the direction of flow of the fluid through the nozzle. Thenozzle of this invention, is provided with a plurality of chambers thatare open to the inner portion of the nozzle, and are open at port endsto a reference pressure, for instance the atmosphere. Means are providedfor selectively closing off one or more of these chambers from access tothe atmosphere. When a chamber is closed off from the atmosphere, thefluid flowing through the nozzle creates a pressure decrease in thechamber so closed off, and causes the fluid flow to be directed towardthe wall whose chamber is so closed off. When a chamber thus closed offis subsequently opened to the atmosphere, and another of the chambers isclosed off, the pressure imbalance will cause the fluid flow to bedeflected to the wall whose chamber is then closed off.

A primary object of this invention, then, is to provide an improvedPrandtl nozzle and control apparatus therefore. Another object of thisinvention is to provide a control apparatus for a Prandtl nozzle thatdoes not require the application of externally supplied fluid impulsesfor controlling the direction of fluid flow. Still another object ofthis invention, is to provide a mechanical apparatus for opening andclosing ports to control chambers in a Prandtl nozzle for controllingthe direction of fluid flow therein. Still another object of thisinvention, is to provide a simply constructed Prandtl nozzle for use indocument-handling equipment. These and other more speciflc and detailedobjectives will become apparent from a consideration of the descriptionof the preferred embodiment when viewed in light of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of theimproved Prandtl nozzle and controls therefore,

FIG. 2 is an end view showing the shape of the exhaust portion of thePrandtl nozzle;

FIG. 3 illustrates a face view of one type of mechanical control elementthat is used for opening and closing the control ports;

FIG. 4 illustrates a single control element of the type illustrated inFIG. 3 for controlling a plurality of ports; and

FIG. 5 is a diagrammatic representation of the improved Prandtl nozzlewhen used for separating documents in a document-handling apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a diagrammatic view ofthe Prandtl nozzle of this invention with its associated controlapparatus. The nozzle 10 has a neck portion 12 coupled to a conduit 14which in turn is coupled to fluid source 16. characteristically thefluid can be considered to be air. Fluid source 16 has associatedtherewith a pressure control 18 for establishing the fluid pressure tobe established from the fluid source 16 in conduit 14. It should benoted that for certain applications, the pressure control 18 can be of avarying type control such that the fluid pressure in conduit l4 resultsin a pulsating fluid flow into neck 12. As the fluid flows through neck12, it tends to follow the path indicated by arrow 20 out of the exhaustportion 22 of nozzle 10. Chambers 24, 24' are located at the sides ofneck 12 in the area of the nozzle where the exhaust portion 22 expandsoutwardly.

The operation is such, that the chambers 24, 24 can control thedirection of fluid flow out of exhaust portion 22. The chambers 24, 24have ends 26, 26' open to the inner portion of nozzle 10. The outer ends28, 28, otherwise referred to as ports are subject to being open to theatmosphere. In order to control the direction of fluid flow, the portsare selectively opened and closed. In order to cause the air to flow inthe downward direction indicated by arrow 30, it is necessary only toclose off port 28 from communication with the atmosphere. This causes areduced pressure in chamber 24, thereby tending to cause the airstreamto adhere to the lower wall of exhaust portion 22. During the closing ofport 28, to cause the fluid to proceed in the direction arrow 30, it isnecessary that port 28' be open. In order to switch the direction offluid flow from that indicated by arrow 30 to the direction indicated byarrow 32, it is necessary only to open port 28 and close port 28. Again,closing port 28' will result in the lowered pressure in chamber 24',thereby causing the wall-attachment effect of the fluid to the uppersurface of exhaust portion 22. It is of course clear, that in switchingthe fluid flow from the direction of arrow 30 to the direction of arrow32 that the stream of air will traverse the path upwardly at the exhaustportion 22 of the nozzle, as indicated by arrows 34, 20, and 36. It canbe seen, therefore, that in order to cause the fluid flow to moveupwardly and downwardly, it is necessary to only to alternatively openand close ports 28 and 28'.

FIG. 2 illustrates an end view of the exhaust portion 22 of the nozzle.The opening 40 is in neck portion 12 and communicates with the conduit14.

The ports 28 and 28, are controlled by control elements 42 and 42',respectively. Turning attention briefly to FIG. 3, there is shown anelement 42 that can be used advantageously to control ports 28 and 28'.There is shown a circular element 42 having apertures 44 therein. Thedotted circular portion 28"illustrates the location of the element 42with respect to port 28. As element 42 is caused to rotate about axis46, the apertures 44 proceed to periodically expose port 28 to theatmosphere. When element 42 is in the position shown in FIG. 3, port 28is blocked. The diameter D of apertures 44 is somewhat less than thespacing D+X between apertures 44 in order to permit time for the streamof fluid flow to be switched upwardly and downwardly. Control elements42 and 42 can be driven for instance by port B control element 48 andport A control element 50 respectively. A synchronizing control 52 canbe coupled, as indicated by dashed lines 54 and 56 to com trol elements50 and 48 respectively. The synchronizing control 52 can be utilized toassure the alternate opening and closing of ports 28 and 28'. Thecontrols 48 and 50 can be geared linkages, pulley linkages, fluidicmotors, or any other wellknown devices for causing a predeterminedmovement of control elements 42 and 42'.

It is of course clear that the rotary motion of control elements 42 and42' can be replaced by reciprocating members that merely move back andforth across ports 28 and 28', or other movable device for opening andclosing the ports.

FIG. 4 illustrates a partially broken away alternative arrangement forcontrolling the ports of a Prandtl nozzle as used in this invention. InFIG. 4 there is shown a single rotary element 42 having severalapertures 44 therein. In this arrangement, a single rotatable element 42is arranged to cooperate with a pair of chambers 24-4 and 24'4. In thisarrangement, it can be seen that chambers 24-4 is cooperating with thesolid portion of element 42 while chamber 24'-4 is in cooperation withaperture 44 thereby being exposed to the atmosphere. In thisconfiguration, a single drive can be utilized for driving element 42,thereby further simplifying the control structure. In this arrangementit is necessary only that chambers 24-4 and 24'-4 have their portportions directed to the side to permit cooperating with the singleelement 42.

The improved Irandtl nozzle and control apparatus of this inventionfinds use in document-handling equipment. FIG. 5 shows an arrangementwherein the exhaust portion 22 of nozzle is directed at a stackedplurality of documents 60 which are retained in a predeterminedrelationship, such as by a pin 62. In this arrangement, it can be seenthat fluid flow leaves the exhaust portion 22 and is switched upwardlyand downwardly by the alternate opening and closing ports 28 and 28,there is a turbulence generated at the ends of documents 60, therebycausing the documents to separate for allowing the fluid to passtherebetween. Many document-handling devices provide for holdingdocuments in a predetermined relationship by a plurality of pins 62which are selectively withdrawn for permitting a selected one of thedocuments to be removed from the stack. This end-coding of documents iswell known in the prior art as is the coded withdrawal of pins forpermitting extraction of a selected document. The extraction may be donemanually or by machine. It can be pointed out that while the documentsare shown in the horizontal position in FIG. 5, that they can also besuspended vertically with the improved nozzle being directed downwardlyat the upper ends of document 60. This provides the advantage that thefluid flow need not support the weight of the documents but can be usedmerely to separate the documents in a horizontal manner. Both systemsfind advantageous use. It will be recalled from the consideration ofFIG. I that pressure control 18 can be used to cause fluid source 16 toprovide a pulsating fluid flow to conduit 14 and thence to the nozzle10. The combination of the pulsating fluid and the movement of the fluidupwardly and downwardly by the nozzle provides an advantageousarrangement for keeping documents 60 separated.

Having, therefore, in the foregoing description fully set forth theimprovements and advantages of this invention, it is clear that thestated objectives have been achieved. It being understood that variousmodifications will become apparent to those skilled in the art uponviewing this discussion and the drawings, without departing from thespirit and scope of the invention, what is intended to be protected byLetters Patent is set forth in the appended claims.

We claim:

1. An improved nozzle comprising neck means for receiving fluid; exhaustmeans coupled to said neck means and having outwardly extending walls;chamber means positioned in said walls and in fluid communication withsaid fluid and an ambient fluid pressure; and control means forselectively blocking said fluid communication with said ambient fluidpressure in said chamber means for causing a fluid pressure imbalancefor causing change of direction 0 flow of said fluid in said exhaustmeans.

2. A nozzle as in claim 1 wherein said chamber means includes a pair ofchambers each associated with one of said outwardly extending walls, andsaid control means includes movable means for selectively blocking andunblocking said chambers, the blocking of one of said chambers causingthe direction of fluid flow to be deflected toward the one of said wallsassociated with said one chamber.

3. A nozzle as in claim 2 wherein said movable means includes a rotarymember having a plurality of apertures therethrough, said rotary memberarranged for opening and blocking said pair of chambers.

4. A nozzle as in claim 2 wherein said movable means includes a pair ofrotary members, a different one of said pair associated with each ofsaid pair of chambers, each of said rotary members having a plurality ofapertures therethrough said rotary members arranged for opening andblocking said associated one of said chambers.

5. A nozzle as in claim 4 and further including synchronizing means forsynchronizing movement of said pair of rotary members.

6. A nozzle as in claim 2 and further including fluid pressure controlmeans for causing pulsating fluid flow in said neck means.

1. An improved nozzle comprising neck means for receiving fluid; exhaustmeans coupled to said neck means and having outwardly extending walls;chamber means positioned in said walls and in fluid communication withsaid fluid and an ambient fluid pressure; and control means forselectively blocking said fluid communication with said ambient fluidpressure in said chamber means for causing a fluid pressure imbalancefor causing change of direction of flow of said fluid in said exhaustmeans.
 2. A nozzle as in claim 1 wherein said chamber means includes apair of chambers each associated with one of said outwardly extendingwalls, and said control means includes movable means for selectivelyblocking and unblocking said chambers, the blocking of one of saidchambers causing the direction of fluid flow to be deflected toward theone of said walls associated with said one chamber.
 3. A nozzle as inclaim 2 wherein said movable means includes a rotary member having aplurality of apertures therethrough, said rotary member arranged foropening and blocking said pair of chambers.
 4. A nozzle as in claim 2wherein said movable means includes a pair of rotary members, adifferent one of said pair associated with each of said pair ofchambers, each of said rotary members having a plurality of aperturestherethrough said rotary members arranged for opening and blocking saidassociated one of said chambers.
 5. A nozzle as in claim 4 and furtherincluding synchronizing means for synchronizing movement of said pair ofrotary members.
 6. A nozzle as in claim 2 and further including fluidpressure control means for causing pulsating fluid flow in said neckmeans.